There are many types of lighting fixtures for the home or office which are known in the art. These include Edison based fixtures, surface mounted fixtures, track-lighting fixtures, and recessed fixtures. These fixtures have traditionally come in three types: incandescent, fluorescent, and high intensity discharge (HID) lights. All three suffer from inefficiency, relatively short life, and high heat dissipation. For example, incandescent lamps produce in the area of 14 to 17 lumens per watt. In addition, incandescent light sources use a thin filament which glows when heated by electrical power and tends to burn out easily. Typical, incandescent lamps have to be replaced every 2000 hours. Fluorescent lamps are an improvement over incandescent lamps, producing 50 to 120 lumens per watt, and lasting about 15,000 hours. HID lamps last about 20,000 hours.
To overcome inefficiency and to extend lifetime, LED-based lighting fixtures have been introduced. A white light can be produced by combining a blue led with a phosphor, or by combining red, green, and blue LEDs. These combination LEDs can be formed into incandescent-like bulbs and recessed cylindrical or rectangular fixtures. In order to avoid replacing the large base of existing incandescent-based recessed lights, LED light fixtures can be designed to be retrofitted into existing fluorescent rectangular or cylindrical “can” incandescent or fluorescent fixtures. The LED recessed lamps in the prior art, however, operate generally at low wattages, typically about three watts. If the wattage is raised to increase brightness, say to about 5-50 watts, the increased heat dissipation causes the LEDs to drift out of current-voltage specification, thereby introducing unwanted color variations and even failure. In some circumstances, depending on the thermal environment of an LED recessed lamp, ventilation may be needed for power dissipation as low as 2 watts (or a light output of about 100 lumens or more).
As such, there is a need in the art for an improved retrofittable LED-based recessed light that can operate at relatively high wattages without incurring color variations or risking failure at high output power.